I will examine the relationship between upper airway muscle (UA mm), diaphragmatic activity and ventilation during all states of waking and sleep. State-related changes in muscle and ventilatory responses to stimuli will also be studied. Cats will be chronically implanted to record standard sleep parameters and muscles. For studies of ventilation, cats will also be prepared with a chronic tracheal fistula and recorded while intubated and restrained. State-related changes in UA mm function are implicated in the pathogenesis of sleep apneas, a life-threatening syndrome most common in adult men. To further clarify the role of UA mm atonia which normally occurs in paradoxical sleep (when most frequent and severe apneas occur) we will repeat all the above studies in cats which have received pontine lesions abolishing the atonia of paradoxical sleep. This preparation, which has been extensively studied by the principal investigator, has previously proved useful in studying the role of atonia in state-related changes in thermogenesis and should be equally useful in establishing the importance of atonia in state-related changes in respiration.